12-25

Nitrosamlnes—compounds derived from the reaction of nitrite with
amines—are carcinogenic in numerous species of laboratory animals and
mutagenic in several experimental systems. Nitrate appears to be
neither carcinogenic nor mutagenic, whereas nitrite is probably not
directly carcinogenic, but it is mutagenic in microbial systems. There
is some inconclusive epidemiological evidence that nitrate, nitrite,
and N-nitroso compounds play a role in the development of gastric and
esophageal cancer.

Many of the naturally occurring substances discussed in this
chapter have been found to be carcinogenic in laboratory animals and/
or mutagenic in bacterial and other systems, thereby posing a potential
risk of cancer in humans. However, there have been no pertinent epi-
demiological studies concerning their impact on -humans except for those
on aflatoxins and those on nitrate, nitrite, and N-nitroso compounds.
The compounds thus far shown to be carcinogenic in animals have been
reported to occur in the average U.S. diet in small amounts; however,
there is no evidence that any of these substances individually makes a
major contribution to the total risk of cancer in the United States.
This lack of sufficient data should not be interpreted as an indication
that these or other compounds subsequently found to be carcinogenic do
not present a hazard. Further investigations are necessary. Efforts
should be made to minimize or avoid the exposure of humans to compounds
that are carcinogenic or mutagenic in experimental systems.